This invention relates to a process for removing an organic impurity from an aqueous solution, as by means of a sorption agent.
Sorption agents known to be used for purifying aqueous solutions are, for instance, active carbons, sulfonated carbon and ion-exchanging resins. In this connection it is known from the published Netherlands Patent Application No. 128,345 that colorants may be removed by means of a cation-exchanging resin containing sulfonic acid groups, carboxylic acid groups, phosphonic acid groups or phosphinic acid groups, with the matrix having a macroporous sponge structure. Such a structure was considered necessary because the cation exchangers known at that time were regarded as insufficiently effective (see Ind. & Eng. Chem. 41 (1949), 2521) Furthermore, from the Netherlands Patent Application No. 7,107,198 it is known that a sugar solution may be purified by bringing it into contact with a cation exchanger which has an acidity (pK.sub.a) in the range of 3 to 6, as a result of which in the sugar solution a buffered medium having a pH value between 3 and 5 if formed.